ECN publication
Range of loss mechanisms accessible by illuminated lock-in thermography (ILIT)
Published by: Publication date:
ECN Solar Energy 1-6-2005
ECN report number: Document type:
ECN-RX--05-035 Conference Paper
Number of pages: Full text:
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Presented at: 20th European Photovoltaic Solar Energy Conference and Exhibition, Barcelona, Spain, 6-10 juni 2005.


Illuminated Lock-In Thermography (ILIT) was introduced as a further development of Dark Lock-In

Thermography (DLIT) in 2004 and allows to measure under conditions considerably closer to real operation conditions of

solar cells. Recently, a number of different modes were developed, that differ in the measurement conditions chosen.

This contribution investigates favorable measurement conditions for the most important parameters of a solar cell. It will be

shown that adapted modes of Lock-In Thermography are well suited for the investigation of linear and non-linear shunts,

bulk material quality and losses due to series resistance as e.g. contact resistance and inappropriate metalization patterns.

Bulk material quality is best investigated under open circuit conditions (VOC-ILIT), whereas series resistance problems

dominate the Thermography image under short circuit conditions (JSC-ILIT). Shunts on the other hand tend to dominated the

measurement at intermediate to high voltages, thus offering the possibility to distinguish between losses due to shunting and

due to series resistance. Finally, good agreement between contact resistance images obtained by JSC-ILIT and emitter

potential maps obtained by Corescan is demonstrated.

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